Strep throat is an infection of the pharynx caused by the bacteria Streptococcus pyogenes. The pharynx is the part of the throat between the tonsils and the larynx, or voice box. The main pathogenic strep groups for humans are A, B, C, D and G. More than 90% of streptococcal disease in humans is caused by Group A beta-hemolytic strep (GABHS).
Streptococcus pyogenes is the bacterium cause of several human infections including acute pharyngitis, impetigo, acute rheumatic fever, scarlet fever, and toxic shock syndrome. The particular bacterium associated with these diseases are beta-hemolytic streptococci (BHS) of Groups A, B, C and G, of which Group A is the most dominant pathogen.
The bacteria that cause streptococcal infection such as strep throat emits toxins that result in inflammation. The predominant locale of the infection is the pharyngeal mucosa. These toxins are central in facilitating the progression of the infection. Symptoms of strep throat include a sore throat that starts suddenly, without runny nose or congestion. The throat is extremely red, and swallowing is painful. White patches typically appear on the tonsils, and lymph nodes in the neck swell. Symptoms may also include fever, headache, loss of appetite and fatigue. Children with strep throat may also exhibit nausea, vomiting and abdominal distress.
Existing methodologies for determining when severe sore throat symptoms may be a strep infection, such as GABHS, require a visit to a physician's office. The most commonly used test is an antigen-based test, specific to GABHS. These rapid strep tests require a deep swab sample of the mucus in the pharyngeal area, which is prepared using one or two reagent chemicals. The test is considered adequate for Strep A (GABHS) positive readings, and takes about 3-15 minutes. When a negative rapid strep test occurs, it is common practice to perform a laboratory cell culture to confirm or rule out the presence of a Strep A infection. The culture is required owing to a high incidence of false negatives associated with the antigen specificity of current tests. Exemplary of these tests are those disclosed in U.S. Pat. Nos. 4,863,875; 5,374,538 and 6,030,835.
People who may be at risk for serious complications from strep infection include people who have chronic conditions such as diabetes, weakened immune systems or immunodeficiency disorders. Serious complications from untreated strep infection include otitis media, peritonsillar abscesses, meningitis, peritonitis, scarlet fever and rheumatic fever. Prompt diagnosis and treatment with antibiotics are the best ways to prevent infection spread and complications.
The current rapid tests require swabbing the back of the throat to obtain a mucus sample and transferring the sample to a container or test paper. The swabbing of the throat represents a traumatic event for a patient, as well as the healthcare worker. The collection of a throat swab is made all the more difficult with pediatric patients who represent a strep-vulnerable population. The addition of two or more reagents is required before a visual check for the development of a color indicator. The color development is a result of GABHS antigens reacting with the antibodies introduced by the test. The methodology is sufficiently complicated to require a laboratory technician to properly perform the test.
Thus, there exists a need for a non-antigen specific rapid test for the presence of beta-hemolytic streptococcus in a bodily fluid that is operative independent of a mucosal swab. Additionally, there exists a need for a rapid beta-hemolytic streptococcus test that is amenable to home use as a prescreen for consultation with a health professional.